Samsung Electronics Co. is preparing to release a smartphone in Russia and India based on the company's own operating system, people familiar with the matter said, the latest step in Samsung's push to compete directly in mobile software with Google Inc. and Apple Inc.

The South Korean company is planning an event in Moscow in the coming weeks to introduce a smartphone running on the Tizen operating system, the people said. The Russia release would be presented at an event similar to the format that Samsung uses to unveil...